Microhardness testing instrument



June 17, 1947' H. Ril-:PERT ET AL` MICRO HARDNESS TESTING INSTRUMENTFiled March l0, 1959 llllllllllw 13 `unh .3

=vll////////// v, 4 W Y ,d-WM

Patented June 17, 1947 2,422,634 v MICROHARDNESS TESTING INSTRUMENTHermann Riepert and Heinrich Broschke, Wetzlar, Germany; vested in theAttorney General of the United States Application March 10, 1939, SerialNo. 260,905

In Germany April 26, 1938 Sections 3 and 14, Public Patent expires 1Claim.

This invention relates to improvements in portable hardnesstestinginstruments. The object of the invention is tov provide arelatively small compact testing mechanism vwhich shall be especiallywell adapted to be used in combination with a microscope as an integralpart thereof. The testing mechanism is characterized, among otherfeatures, by the fact that the testing or penetrating member is sosupported that it opcrates under its own weight during the testingoperation.

Some prior hardness testing devices or ma; chines operate with twoweights. When the testing member contacts the object a rst smallerweight is placed upon or caused to operate upon the testing member toeffect a first penetration into the object. Thereafter a heavier weightis used for the same purpose. The difference in penetration is thenmeasured by suitable well known means.

Devices which operate inthis manner must be constructed verysubstantially. They are relatively heavy and expensive. They cannot beused for testing heavy or immovable objects because the testing deviceitself is not portable as this term is understood. It has therefore beenproposed to use smaller hardness testingdevices ofthe portable type.With such a device the operation is carried out by placing the deviceupon the object and the weight of the entire device itself is utilizedas a first weight to cause penetration of the object. Thereafter aweight is causedto fall upon the penetrating member in order to obtain asecond deeper penetration. The difference in penetration is measured bywell known means. The German Patent 572,671, March 20, 1933 refers tothese types of devices.

Other devices are spring actuated and suffer from inexactness due touneven uncontrollable tension of the spring. Still other devices utilizeweights placed upon levers or arms, and it has been found that they arenot sufiiciently accurate.

In the present invention` the hardness testing instrument or device isconstructed so as to be incorporated in a microscope and carried aboutand used as conveniently as such instruments are customarily used. Thepenetrating testing element is supported in such a manner that when themicroscope is placed upon an object to be tested, the testing elementautomatically comes to rest upon the object under its own weight. Theengagement of the testing element with the object is utilized to open anelectric circuit with means to signal that the element is supported bygravity and that the operation may l begin.

Law 690, August 8, 1946. April 26, 1958 Y Thereafter the penetrating ofthe object is done by the testing element under its own weight.

Should it happen that the testing element by contacting the object israised too high so as not to be able to function under its own weight,the circuit is again closed and signals this condition. An additionalhand weight member may be provided to increase momentarily the weight ofthe testing element. The invention is illustrated in the accompanyingdrawing which is a general view of the instrument with parts broken awayand parts in section. Only so much of the microscope is shown as isnecessary for understanding the invention.

in the drawing the microscope is identified by the usual microscope tubel. To the bottom thereof` there is secured a bracket 25 having acentral'bore 32 in alinement with the microscope tube I.V The bracket 25also supports ball bearing means 34 for the support of a sliding member2 which supports the microscope objective 3 and the hardness testingdevice 4. Preferably the arrangement is such that either the objectiveor the testing device may be moved in under the microscope tube. In theone case to conveniently support the testing device centrallyof theapparatus as shown, in the other case to align the tube and theobjective. It is not necessary for practising the invention that thisparticular arrangement be used. It will be observed however that bycombining the hardness testing device with the microscope it is an easymatter to observe the results of the testing by means of the microscopeby merely sliding the objective in under the tube. It will also be clearthat inasmuch as the tube is adjusted in the usual manner in microscopesit is not possible to use falling weights or like means upon the testingdevice, nor weights to such an extent as will disturb the tubeadjustment.

Referring to the drawing the testing device comprises the general casing4 which is supported in the slide 2. The casing supports a plate i6which is insulated as at 9. The plate supports the testing element 1which is in the form of a vertical shaft. Above the plate I6 this shaftcarries a contact disk I4. Below the plate the shaft carries anothercontact disk I3. The distance between the disks is somewhat greater thanthe thickness of the plate I6. The testing element carries at its lowerend a suitable testing penetrating point 6 and above the latter thetesting element is enlarged to form a weight 8. The testing element isguided vertically by two thin lamellae Il and I2. These are ofsufficient strength to guide the element 'I against tipping providesupporting means for the testing element but they are not strong enoughto interfere with so arranged that the operator may observe the the freevertical movement of the element. An element directly. Such analternative embodiadditional loose weight4 I9 is provided to rest uponment is not shown.

the weights when necessary. The weight I9 may 5 We claim:

be lifted orf the weight 8 by a ring 20 provided In a microhardnesstesting instrument as dewith a handle 2l accessible from the outside ofY scribed, a microscope having a microscope tube, the casing 4. anobjective and a testing device including a The plate I 5 is connected bya wire I5 to a testing element, a bracket upon the lower end of sourceof electric current 28and'a'1amp I8. The 10 said tubev having acentrally extending vertical return wire of the circuit may begroundedas bore in 'alinement with said tube, horizontally at I'l. The numeral 5indicates the object 30 is disposedV guiding means in said bracket atthe a switch. f bottom of` and intersecting said bore, a slidable Whenthe operator intends to use the instrumember supported in said guidingmeans, means ment he moves the member in its supporting l5 forsupporting said testing device and said ob- A`upon the object 5. Thelcircuit remains closed 20 supporting means including means forsupportcircuit is broken at I4-I5, the lamp goes out and ing broughtinto Contact under its own Weight thus signals the beginning of thetesting opera- 2'5 with an object .to be tested and which said ele-4tion. 'Should the circumstances be such that the ment automaticallyreassumes upon removal from element 7 islifted too high, then thecircuit is the object, means for increasing the weight of thssignalstothe operatorto adjust the1nstruv30 by said 'element to indicate itsrespective said has been placed upon the object, the circuit will yHERMANN RIEPERT.

be broken as aforesaid and now the testing ele- Y Y Y HEINRICH BROSCHKE.ment 'I will rest upon the object under its own s s weight to cause thenecessary penetration of the 35 REFERENCES CITED Pb'ht -5- .H110addtna'l Weight is necessary the The following references are of recordin the `ottitator lifts thetgight i9 of 'the weight t, and me 0, thispatent:

under the microscope tube `for examination of UNITED STATES PATENTSthepenetration point or area of 'the object. 40 Number Name Date .Fromthe `1orgoingy it will be noted that the '1,335,972 Wson Nw 1J 1932testine elefrleht'isf''mally Supportedby gravity 1,478,621 smith et al.Dec. 25, 1923 anais automatically lifted out O'fsifts sup- 2,-13s,411Tomebohm N0v29, 193s po'rted'position andbrought to rest by gravity 11,512,192 Benko Oct. 21, 1924 `tiroir'the object eithrjunder its ownnormal 45 1,985,916 Coates et a1. Jan. 1, 1935 weight ,or withth'elod'seWeight added. The elec- 1,452,910 Moore et ai Apr. 24, 1923 tric signalmeansseve to notify the Operator 2,003,910 Stephenson June 4, 1935,thatthe testine element is in proper 'Operative 1,875,134- P'nund Aug.30, 1932 .position for the test. The device is small, corn- 50'1,346,943 Desautefls Feb, 23J 1932 pact, easily portableandconveniently incorpo- Y rated. mts the microscope structure. FOREGNPATENTS y It will further be clear that vthe operation of Number CountryDate the testing element or the position thereof need 467,806 GreatBritain June 23, 1937 not necessarily 'be signalled in the manner dis-464,005 Great Britain 'Apn 9, 1937 closed. T t is'within the scopeof theinvention to 55 v195,094 Germany Feb. 6, 1908

